Foam concentrate proportioning system and methods for rescue and fire fighting vehicles

Abstract

A system and method of maintaining a desired additive to water ration in a fire-fighting system including a water flow sensor configured to measure the water flow rate, a water pump, a hydraulic pump, a linear hydraulic cylinder driven by the hydraulic pump, an additive pump mechanically coupled to the linear hydraulic cylinder; and a pump displacement sensor configured to sense the position of the additive pump, the pump displacement sensor being in communication with the water flow sensor to maintain a pre-determined ratio of additive to water.

What is claimed is:  
     
       1. An additive proportioning system for a firefighting vehicle comprising: 
       a source of pressurized water;  
       a source of additive;  
       a water flow sensor responsive to the source of pressurized water and configured to measure a water flow rate;  
       a hydraulic pump;  
       an actuator fluidly connected to and driven by the hydraulic pump;  
       an additive pump mechanically coupled to the actuator and fluidly connected to the source of additive; and  
       a pump displacement sensor configured to sense the position of the additive pump, said pump displacement sensor being in communication with the water flow sensor to maintain a pre-determined ratio of additive to water.  
     
     
       2. A system as in  claim 1   
       wherein the hydraulic pump is driven by an auxiliary transmission.  
     
     
       3. A system as in  claim 1   
       wherein the hydraulic pump is driven by a power take-off of the vehicle.  
     
     
       4. A system as in  claim 1  further comprising: 
       a programmable logic controller.  
     
     
       5. A system as in  claim 4   
       wherein the water flow sensor sends an input signal to the controller.  
     
     
       6. A system as in  claim 4   
       wherein the pump displacement sensor sends an input signal to the controller.  
     
     
       7. A system as in  claim 4   
       wherein the water flow sensor and the pump displacement sensor send an input signal to the controller.  
     
     
       8. A system as in  claim 1  further comprising: 
       a proportioning valve fluidly coupled to a source of hydraulic fluid and configured to drive the actuator.  
     
     
       9. A system as in  claim 8   
       wherein the proportioning valve is in communication with a programmable logic controller.  
     
     
       10. A system as in  claim 9   
       wherein the controller sends an output signal to the proportioning valve.  
     
     
       11. A system as in  claim 1   
       wherein the additive is a thixotropic substance.  
     
     
       12. A system as in  claim 1  further comprising: 
       multiple sources of additive.  
     
     
       13. A system as in  claim 1 , further comprising: 
       a means for mixing the additive with the water.  
     
     
       14. A system as in  claim 13   
       wherein the means for mixing the additive with the water is a manifold.  
     
     
       15. A system as in  claim 1   
       wherein the actuator is a hydraulic cylinder.  
     
     
       16. A system as in  claim 1   
       wherein the pump displacement sensor is a linear variable displacement transducer.  
     
     
       17. A system as in  claim 1   
       wherein the additive pump is a piston pump.  
     
     
       18. A system as in  claim 17   
       wherein the additive pump is a double-acting piston pump.  
     
     
       19. An apparatus for mixing water and an additive in a firefighting vehicle, the apparatus comprising: 
       a programmable logic controller;  
       a water flow sensor responsive to a source of pressurized water and electronically coupled to the controller;  
       a hydraulic pump;  
       an actuator fluidly connected to and driven by the hydraulic pump;  
       an additive pump mechanically coupled to the actuator and fluidly connected to a source of additive; and  
       an additive pump displacement sensor configured to sense the position of the additive pump, the pump displacement sensor being in communication with the controller.  
     
     
       20. An apparatus as in  claim 19   
       wherein the hydraulic pump is driven by a hydraulic pump motor.  
     
     
       21. An apparatus as in  claim 19  further comprising: 
       a proportioning valve fluidly connected to the hydraulic pump and the actuator.  
     
     
       22. A system as in  claim 21   
       wherein the proportioning valve is in communication with the controller.  
     
     
       23. An apparatus as in  claim 22   
       wherein the controller provides communication between the water flow sensor, the proportioning valve, and the additive pump to maintain a pre-determined ratio of additive to water.  
     
     
       24. An apparatus as in  claim 19 , further comprising: 
       a means for mixing the additive with the water.  
     
     
       25. An apparatus as in  claim 24   
       wherein the means for mixing the additive with the water is a manifold.  
     
     
       26. An apparatus as in  claim 19   
       wherein the actuator is a hydraulic cylinder.  
     
     
       27. An apparatus as in  claim 19   
       wherein the pump displacement sensor is a linear variable displacement transducer.  
     
     
       28. An apparatus as in  claim 19   
       wherein the additive pump is a piston pump.  
     
     
       29. An apparatus as in  claim 28   
       wherein the additive pump is a double acting piston pump.  
     
     
       30. An apparatus as in  claim 19  wherein 
       wherein the programmable logic controller adjusts the additive pump speed in response to the sensed direction of the additive pump.  
     
     
       31. An additive proportioning apparatus comprising: 
       an actuator;  
       an additive pump coupled to and driven by the actuator;  
       wherein the actuator is coupled to a linear variable displacement transducer that senses the position of the additive pump.  
     
     
       32. An apparatus as in  claim 31   
       wherein the additive pump is a positive displacement piston pump.  
     
     
       33. An apparatus as in  claim 32   
       wherein the additive pump is a double acting pump.  
     
     
       34. An apparatus as in  claim 31   
       wherein the actuator is a positive displacement piston pump.  
     
     
       35. An apparatus as in  claim 31   
       wherein the additive is a thixotropic substance.  
     
     
       36. A method of maintaining a desired additive to water ratio in a fire-fighting system comprising the steps of: 
       inputting into a controller a pre-determined additive to water ratio;  
       sensing the water flow rate;  
       computing the additive flow rate by determining the position of a positive displacement piston pump at at least two defined intervals;  
       computing the actual additive to water ratio based on the sensed water flow and additive flow rates;  
       comparing the computed ratio with the input ratio; and  
       adjusting the output of the positive displacement pump to substantially match the input ratio.  
     
     
       37. A method as in  claim 36 , further comprising the steps of: 
       re-sensing the water flow rate;  
       re-sensing the additive flow rate;  
       re-computing the actual additive to water ratio;  
       re-comparing the computed ratio with the input ratio; and  
       re-adjusting the output of the positive displacement pump.  
     
     
       38. A method as in  claim 36   
       wherein the additive is a thixotropic substance.